A concentration facility, hereinafter referred to as “Concentrator,” is typically defined by a combination of one or more unit operations. Concentrators are usually large-scale facilities capable of processing thousands of tons of ore per day.
To recover metals and other minerals for use in industrial processes, significant quantities of ore or rock are mined, crushed, pulverized and processed. Nowadays, it is often desirable to process minerals with contents above 35% iron to obtain concentrates with up to 68% iron. Such processes are carried out with dry and/or partially wet processing stages. Dry processing normally goes from mining (extraction of the ore in the mine) up to sieving and crushing operations. When processing natural fines from ores, a wet processing stage is conducted after the crushing operation and involves the addition of large quantities of water. This wet stage begins at grinding. Grinding is necessary to release metals and minerals from the ore or rock. Therefore, the mining industry produces large quantities of fine ore or rock particles where such fine grained wastes are known as “tailings.”
The most common ore concentration process, capable of processing large quantities of ore, is flotation, carried out in mechanical cells or flotation columns. Flotation may require a desliming stage, which consists of the extraction of the natural ultrafines and can include extraction of those generated in the grinding process. This is done on a wet basis and requires the movement of large volumes of water, as well as the placement of sandy tailings and slimes from the process in dams.
FIG. 1 shows a flowchart typical of a known process in which all of the material originating from the mine is processed for the production of concentrates.
FIG. 2 shows a flowchart used for processing more complex minerals that require a second stage of grinding to guarantee the liberation of iron ore from the gangue.
The process of reverse flotation is already industrially used at various plants and companies.
The process of concentration after the first grinding stage, as described in FIG. 2, can be flotation or wet high intensity magnetic separation.